Variable pressure fluid actuated brake beam compensation



Aug. 19, 1958 w. ERNST 2,848,034

VARIABLE PRESSURE FLUID ACTUATED BRAKE BEAM COMPENSATION Filed May 19, 1955 IN V EN TOR.

WALTER ERNST W 7o nuw ATTORNEYS United States Patent VARIABLE PRESSURE FLUID. ACTUATED BRAKEBEAM COMPENSATION Walter Ernst, Dayton, Ohio, 'assign'or to The Commonwealth Engineering Company of Ohio, Dayton, Ohio, a corporation of Ohio Application May 19, 19 55,-Serial No. 509,491

4 Claims. (Cl.153'-"2 1) This invention relates to presses of thenature of bending brakes and similar pressing and bending mechanisms characterized in having long platens or pressing members. In particular, this invention is concerned with'abrake or press having a long platen or pressing member in which the pressing member is subject to undesired deflection in use.

In most bending brakes, and in certaintypes of presses, both hydraulic and mechanical, the pressing member is relatively long and narrow in order to permit the'machine with which it is associated to handle large work. Such large work might consist of a large or long sheet ofmetal that was to be formed or bent.

A pressing member or platen of such length ordinarily has the pressing force exerted thereon at spaced points, generally near the opposite ends thereof whereby the platen or pressing member can be moved toward or away from the bed or stationary pressing member in parallelism therewith.

Such an arrangement is satisfactory for bending material and for forming material but involves the disadvantage that, in substantially all presses of this nature, unless the platen is made extremely large and heavy, it will tend to deflect between the points to which the pressing force is applied under normal service. This tendency is, of course, increased where the work being operated is narrower than the distance between the saidpoints of application of the pressing force.

Deflection of the nature referred to of the pressing member or platen is undesirable since it results in improperly shaped work pieces. p t

In order to counteract this tendency of the pressing members or platens to deflect, they are generally cambered or formed so as to be slightly' convex toward the bed or stationary pressing member whereby a predetermined deflection upwardly in the region of the center of the platen will provide the proper configuration thereof to produce a work piece that is shaped according to specifications.

The fundamental fault of the described arrangement for counteracting the inaccuracies introduced by deflection of the press platen or pressing member, is that the amount of camber built into the platen in this manner, will only effect a proper correction for one given predetermined loading.

For a load less than this predetermined loading, the camber of the platen is too great, and for loads greater than the said predetermined loading, the camber is insuflicient completely to counteract the tendency of the platen to deflect.

Having the foregoing in mind, it is a primary object of the present invention to provide an arrangement in connection with bending brakes and presses having long platens that will prevent undesired deflection of the pressing member or platen under load.

Another object of this invention is the provision of a method of operating a press brake such that any deflec- 2,848,034 Patented Aug. 19, 1958 tion of the press platen or beam under load-is counteracted.

Another object of this invention is a provision of an arrangement for preventing the brake beam of a power brake from deflecting upwardly in the center regardless ofthe loading imposed thereon during a work operation.

The foregoing objects referred to above, as well-as still other objects and advantages of this invention, will become more apparent upon reference to the following specification taken in connection with the accompanying drawings, in which:

Figure 1 is a perspective view of a power brake embodying the present invention. v

Figure 2 is a plan sectional view indicated by line 2--2 on Figure 1.

Figure 3 is a front elevational view of a power brake similar to the one illustrated in Figure 1 except for the type of power unit that energizes-the brake beam.

Figure 4 is a diagrammatic view showing a hydraulic circuit for energizing the compensating motor attached to the center ofthe brake beam.

Referring to the drawings more in detail, Figure 1 shows a power brake comprising a frame 10 having a bed portion 12 adapted for cooperation with a vertically rec'iprocable platen, pressing member, or brake beam 14 guided at its opposite ends on vertical guide-ways 16 of the press frame.

In the press frame above brake beam 14 is a shaft 18 adapted for being driven in rotation. Shaft 18 at its opposite ends has throws or eccentrics 20 thereon connected by the rods 22 with the opposite ends of brake beam 14.

It will be apparent that rotation of shaft '18 will be accompanied by vertical reciprocation of brake beam 14. Suitable controls well known in the art can be employed for obtaining rotation of shaft 18 a single revolution at a time.

As has been explained above, brake 14 tends to deflect upwardly at the center when a load is imposed thereon during a working cycle, and according to this invention, this tendency for the beam 14 to so deflect, is counteracted by exerting a downward force on the center of the brake beam during the work cycle and which force is exerted only on the platen and is contained within the platen thereby involving little actual work.

The force, according to this invention, is exerted by a ram 24 extending upwardly into a cylinder 26 and which cylinder is connected by tension links 28 with points 30 adjacent the ends of the brake beam and preferably in the region that the rods 22 are connected thereto.

Hydraulic fluid under pressure is adapted for being supplied to cylinder 26 via conduit 32 to urge ram 24 downwardly therein, against a bearing block 34 carried by the platen.

This downward thrust on ram 24 serves to counteract the tendency for the beam 14 to deflect upwardly in the center so that work formed in the press brake does not come therefrom inaccurate due to this deflection.

The ram 24 may be energized to varying degrees by a simple hydraulic circuit of the nature shown in Figure 4 wherein a pressure source 36 discharges through a pressure regulating valve 38 to conduit 32.

Valve 38 is adjustable by hand-wheel 40 so that any desired pressure can be delivered to cylinder 26 and, thus, any desired downward thrust exerted on ram 24 on the center of brake 14.

In Figure 3 a power brake or a press having a long: platen is illustrated wherein the opposite ends of the platen are connected with the hydraulic motors 42 which have pressure fluid reversibly supplied thereto from a.

reversing valve 44 which is connected to any suitable pressure source.

In Figure 3, the cylinder of the beam or platen 46 is engaged by ram 48 extending into cylinder 50 which is connected by links 52 with the outer ends of the platen or brake beam. Cylinder 50 rather than having an independent pressure source as in the case of cylinder 26, is connected with conduit 52 which leads to the advancing sides of motors 42, so that ram 48 is urged downwardly when the press is on a working stroke, and is idle when the press is retracted.

Furthermore, ram 48 is urged downwardly with a thrust that is proportional to the pressure supplied to motors 42 and, thus, also proportional to the load that is imposed on beam on platen 46. To meet varying conditions, the connection from conduit 52 to cylinder 59 may include a pressure regulating valve 54 so that the pressure supply to cylinder 50 can bear any desired ratio to the pressure supply to motors 42.

It will be appreciated from the foregoing that my invention provides a ready means for counteracting the tendency for a long platen or brake beam to deflect upwardly under load. This means can take the form of the exertion of a downward force on the platen or beam which is proportional to the upward force imposed thereon by the work, as in the case of the Figure 3 arrangement, or it can take the form of a fixed prestressing thrust exerted on the platen or beam in the region thereof subject to deflection as in the case of the Figure 1 arrangement.

It will be understood that this invention is susceptible to modification in order to adapt it to different usages and conditions, and, accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

I claim:

1. In a pressing device having an elongated pressing member and motor means for applying force to said member at spaced points adjacent the ends thereof; an element bearing on the pressing member between said points on the side thereof opposite the side of the working load on the pressing member, and expansible hydraulic motor means carried in its entirety by the pressing member for thrusting said element against said pressing member to counteract the tendency of the member to deflect under load, said hydraulic motor means comprising one part rigid with the ends of the beam and a second part engaging said element, and means for supplying fluid to the hydraulic motor means including means variable in response to the load on said motor means for varying the pressure of the supplied fluid thereby to vary the thrust of the second part on said element so the element is urged against the pressing member with a thrust constantly having a fixed proportion to the load on the pressing member.

2. In a power brake; a brake beam, hydraulic motor means adjacent the ends of the beam for exerting pressing forces thereon, a ram engaging the top of the beam in the region of the center thereof, a cylinder into which the ram extends supportingly connected with the ends of the beam so as to move therewith, and means connected with the advancing sides of said motor means for supplying pressure fluid to the cylinder for thrusting the ram against the beam to counteract the tendency of the beam to deflect under load, said last mentioned means including means for adjusting the pressure ofthe fluid F so supplied to said cylinder.

3. In a power brake; an elongated brake beam, hydraulic motor means adjacent the ends of the beam for exerting actuating forces on the beam, a ram engaging the top of the beam in the region of the center thereof, a cylinder into which the ram extends, tension elements connected at one end to the cylinder and at the other end to the ends of the beam, a source of fluid under pressure, a fluid circuit connecting said source with said cylinder and with said motor means to stress the beam by the ram to counteract the tendency of the beam to deflect under load, and means to vary said stress so it is proportional to said load.

4. In a power brake; a brake beam, hydraulic motors connected to the beam adjacent the ends thereof to reciprocate the beam toward and away from the work, a ram engaging the top of the beam between said motor, a cylinder into which the ram extends, tension elements connecting the cylinder with the ends of the beam, and a fluid circuit interconnecting said motors and cylinder so a supply of fluid to the motors to advance said beam will be accompanied by a supply of fluid to said cylinder to thrust said ram against the beam to stress the beam in a direction to counteract the tendency thereof to deflect under load. 

